According to its advocates, nasal irrigation promotes good sinus and nasal health. Patients with chronic sinusitis including symptoms of facial pain, headache, halitosis, cough, anterior rhinorrhea (watery discharge) and nasal congestion are reported often to find nasal irrigation to provide relief. In published studies, "daily hypertonic saline nasal irrigation improves sinus-related quality of life, decreases symptoms, and decreases medication use in patients with frequent sinusitis",[2] and irrigation is recommended as an adjunctive treatment for chronic sinonasal symptoms.[3][4]

For chronic sinusitis it can be an effective add-on therapy. It is also reported to be an effective measure against chronic sinus symptoms induced by work-place exposure to sawdust.[5] Further evidence suggests that nasal irrigation causes relief for both hay-fever and the common cold. Nasal irrigation could also be an effective treatment for allergic rhinitis[6] and chronicsinusitis.[7]

A daily nasal and sinus rinse with a salt-water solution (a mixture of 0.9% non-iodized sodium chloride and either purified or filtered water warmed to around 98 degrees F/ 37 degrees C, with or without inclusion of a buffering agent such as sodium bicarbonate) has been recommended as both an add-on[8] and primary treatment[9] in such cases and is preferable to the use of corticosteroids except in the most serious cases of acute bacterial sinusitis.[10] Irrigation should be used with caution in infants; however, saline drops or saline as a mist is well tolerated for infants and children with upper respiratory tract symptoms leading to nasal congestion.[11] Filtered water may also be used with an absolute filtration down to .1 micron.[12]

Treatment guidelines in both Canada and the United States recommend use of nasal irrigation for all causes of rhinosinusitis and for postoperative cleaning of the nasal cavity.[13]

Utilizing a sinus rinse and nasal irrigation are well accepted for the temporary relief of the symptoms associated with allergic rhinitis. The mechanism of action is actual flushing of the allergens from the nasal and sinus passages with large volume saline irrigation.[14]

A simple method requiring no specialized equipment is to snort water from cupped hands, but this clears little more than the nostrils. The application of commercially available saline nasal spray is another simple alternative, but it is relatively inefficient for washing away debris, although it may suffice for simple rehydration of mucous and tissues.[17][18]

A simple yet effective technique is to pour salt water solution into one nostril and let it run out through the other while the mouth is kept open to breathe, using gravity as an aid. Jala-neti, which means to cleanse the nose with water, is an old yogic technique from India. The container used to administer the saline is called a "neti pot". This process removes mucus and dirt and clears the nose. A second neti technique known as sutra neti uses a piece of string instead of water.

Neti pots are typically made of metal, glass, ceramic or plastic. They rely on gravity, along with head positioning and repeated practice in order to rinse the outer sinus cavities. Typically they have a spout attached near the bottom, sometimes with a handle on the opposite side.[19]

Various squeeze bottles for nasal irrigation have also been used. The basic design is a plastic squeeze bottle with a straw-like tube. Application of gentle pressure forces the solution through the tube and out of the tip into the nostril. Newer designs utilize valves to prevent backwash contamination. The medical literature demonstrates that most nasal wash bottles become contaminated after use, even with proper instructions for cleaning.[20] The most advanced squeeze bottle utilizes valve technology and a removable top and bottom cap to maximize cleaning and drying to prevent bacterial and mold growth after use.

Bulb syringes may also be used. Bulb syringe irrigation is commonly used for infants and children. Large syringe devices with a specially design nasal tip may also be used for nasal irrigation. Irrigation machines that utilize electric motor-driven pumps are also available. These irrigation devices pump salt water solution through a tube, in connection with a nasal adapter tip designed to seal against the nostril. Some of these machines allow adjustment of water volume/speed by use of an adjustment dial which regulates pump speed and volume per minute. Most of these motorized machines use a pulsatile or pulsating water pumping action at a relatively low, predetermined fixed pulse cyclic rate, designed to match the normal wave rate of healthy, unobstructed nasal cilia.[21] This matched pulse rate is claimed to stimulate the nasal cilia hairs and promote better sinus health, while reducing the severity of allergic reactions.[22] More sophisticated motorized irrigators have two or more pulse cycle settings that adjust the actual pulse cycle (as opposed to a simple volume/speed control, which does not alter the pulse cyclic rate). This design affords the user the option of using a higher pulse cyclic rate when suffering from partially closed sinuses, as in a typical case of acute sinusitis. The efficacy of all motorized pump irrigators has not yet been tested compared to simpler non-motorized mechanical pressure nasal irrigation methods.[23]

While nasal irrigation can be carried out using ordinary tap water, this is potentially unsafe and can be uncomfortable because it irritates the mucous membranes. Therefore, an isotonic or hypertonicsalt water solution is normally used, i.e. water with enough salt to match the tonicity of the body cells and blood. For the same reason, lukewarm water is preferred over cold water, which in addition to irritating nasal membranes can also exaggerate the gag reflex during irrigation. Use of distilled, sterile or previously boiled and cooled water over ordinary tap water is advised. A small amount of baking soda is sometimes employed as a buffering agent to neutralize the pH of the irrigating solution.

Many pharmacies stock pre-manufactured sachets of pharmaceutical-grade salt and baking soda designed to be used with the volume of water in the corresponding device. It is also simple to make a salt-baking soda mixture.[24]

Potential allergens, such as iodine, or contaminants are to be avoided in the sodium chloride, water, and buffering ingredients.[1] Pre-manufactured dosages of salt water flushing solutions can be purchased, or the user can mix non-iodized 'kosher' salt, with or without a buffering agent such as sodium bicarbonate or baking soda. (Table salt frequently is iodized.)

The solution used for irrigation should be distilled, sterile or previously boiled due to the risks involved with using potentially contaminated water.[26] If this is done the procedure is generally safe.[26]

Deaths have been reported as a consequence of using Naegleria fowleri-contaminated water for sinus irrigation.[26] Very few cases of Naegleriasis (in the low hundreds) have ever occurred globally; in the United States, despite two 2011 deaths in Louisiana (both from the same treatment plant) no cases have ever been recorded that involve tap water from normal treated supplies where a water heater has raised the temperature above 120 degrees Fahrenheit. Naegleria fowleri in unboiled or otherwise unsterilized water can cause the brain infection primary amoebic meningoencephalitis (PAM),[27] which carries a 95% risk of fatality.[28]

A much more minor adverse result of using the bottle or mechanized types is occasional vomiting from one's gag reflex being triggered by the slightly pressurized water.[citation needed]

Saline solutions used in nasal irrigation reduce inflammation through osmosis. Swelling is a major factor in sinus dysfunction. Removal of mucus plays an important role in sinus health, and nasal irrigation facilitates this by flushing out thickened mucus that cannot be handled by the cilia.[9][23] improving mucociliary clearance and also removing infected material.[9] Damage to the mucociliary transport system is an important factor in the development of sinonasal diseases, leading to a stasis of mucus.[23] The numerous proteins found in nasal mucus include inflammatory mediators, defensins and many whose function is not understood.[9]

In a study with eight healthy volunteers, solution was transported reliably to ethmoid and maxillary sinuses when it was snorted or applied with a squeeze bottle; a nebulizer was significantly less effective. Sphenoid and frontal sinuses were rarely reached, and not at all with the nebulizer.[18]

Flushing the nasal cavity with salt water has been claimed to promote mucociliary clearance by moisturizing the nasal cavity and by removing encrusted material, although there is no clear evidence to support this.[9]

The earliest record of nasal irrigation is found in the ancient Hindu practice of Indian Ayurveda whose roots are traced to the Vedas. It was customary to perform jala-neti daily, as part of soucha (personal hygiene according to scriptures). The simplest method of nasal irrigation, that is to sniff water from cupped hands and then blow it out, is also a step in the ablution practices (Wudu) of Muslims.